Field of the Inventions
The present inventions relate to torque damper apparatuses for transmitting the driving power of an engine to an output shaft of a vehicle via an input member and damper springs.
Description of the Related Art
A torque converter used in an automobile (e.g., a mainly Automatic Transmission (AT) vehicle) has a torque converter cover for containing operating fluid under a liquid-tight condition in which a pump rotating together with the torque converter cover, a turbine arranged oppositely to the pump, and a stator connected to an one-way clutch. The torque converter is structured so that rotation of the pump is transmitted to the turbine via the operating fluid with amplifying the transmitting torque. Accordingly, the driving power of the engine can be amplified via the operating fluid and transmitted to a transmission and driving wheels of the vehicle.
A lock-up clutch apparatus (e.g., torque damper apparatus) is arranged within the torque converter cover of the torque converter and is intended to reduce torque transmitting loss as compared with that performed via operating fluid by directly connecting the torque converter cover and the turbine at an arbitrary timing. That is, the lock-up clutch apparatus has a clutch piston connected to the turbine and can be moved between a connected position, in which the clutch piston is contacted with an inner wall of the torque converter cover, and a separated position in which the clutch piston is separated from the torque converter cover. When the lock-up clutch apparatus is in the connected position, the torque converter cover and the turbine are directly connected (e.g., mechanically connected) via the clutch piston.
Damper springs are arranged in the usual lock-up clutch apparatus for absorbing the torque variation from the engine when the torque converter cover and the turbine are directly connected. Usually, the damper springs comprise coil springs arranged in a circular arc along the periphery of the clutch piston so that the damper springs can displace (e.g., extension and contraction displacement) to absorb the torque variation transmitted from the engine.
There is one example of a lock-up clutch of the prior art (e.g. disclosed in JP 2002-48217 A) which comprises a piston (e.g., input member) to which engine torque is inputted, elastic members (e.g., damper springs) for absorbing torque variation of torque inputted from the piston, and a rotational output member (e.g., output member) for outputting torque transmitted via the elastic members. The lock-up clutch is structured so that the driving power of engine can be transmitted via the piston, elastic members and rotational output member.
In such a lock-up clutch apparatus of the prior art, a support member is provided which is separated from both the piston and the rotational output member and is rotatable relative to them. This lock-up clutch apparatus is able to set a large torsional angle by arranging the elastic members in series and functioning the support member as an intermediate float member to reduce the whole stiffness of the torque damper apparatus and to improve the vibration absorbing performance.